Apparatus for manufacturing a wiring board and method for manufacturing a wiring board

ABSTRACT

The apparatus for manufacturing a wiring substitute comprises a transporter having a circuit where a sheet is circulated; a screen printer for printing a conductive paste on the sheet; a counter for counting the number of times to print the conductive paste on the sheet; and a distributor for ejecting the sheet from the circuit when the counted number reaches a preset number. Thus, the conductive pillars having uniform properties can be formed automatically on the conductive foil with high productivity.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an apparatus for manufacturing a multi-layeredwiring board, and more particularly to an apparatus for manufacturing amulti-layered wiring board having interlayer connection made byconductive pillars. The invention also relates to an apparatus formanufacturing a multi-layered wiring board having conductive pillarsformed on a conductive foil and an apparatus for manufacturing amulti-layered wiring board having a conductive foil having conductivepillars laminated with an insulating resin layer.

2. Description of the Related Arts

Demands for high-density mounting of electronic elements are increasingas various types of electronic equipment are made compact and highlyadvanced in performance. In response to such demands, a type of wiringboard, such as printed wiring board being used extensively is amulti-layered wiring board which has a laminated structure withinsulating layers and wiring layers alternately overlaid. Themulti-layered wiring board has wiring layers overlaid into amulti-layered structure in order to respond to the demands for highdensity and high performance. Interlayer connection of a plurality ofwiring layers has been established by PTH (plated through hole(s)).

The multi-layered wiring board with via holes such as PTHs forinterlayer connection of wiring layers has a disadvantage that it is noteasy to comply with the demands for high-density mounting.

For example, wiring or mounting of electronic elements cannot be made inan area where a through hole is formed. Therefore, improvement of wiringdensity and high-density mounting is limited. In these years, wiring ofthe printed wiring board is also made to have high density as electronicelements are mounted in high density. When through holes are made tohave a small diameter to comply with fine patterning of wiring, there isa problem that reliable interlayer connection is hardly assured.

In addition, for the interlayer connection with through holes, a throughhole forming step and a plating step are involved, making themanufacturing process lengthy, and it is also disadvantageous in view ofproductivity.

For example, a step for forming through holes requires to make holes oneby one by drilling and takes a long time. Especially, when through holesare drilled so to have a smaller diameter in this step, productivity isextremely lowered. Besides, after forming the through holes, a polishingstep for removing burrs and a plating step are required.

Furthermore, positions where through holes are formed are required to bedetermined with high precision. It is also necessary to consideradhesion of plating to the inner walls of the through holes. Therefore,accuracy and conditions to form the through holes are complex tocontrol, and productivity is decreased.

Especially, when the through hole has a diameter of about 0.2 mm orbelow, its formation takes a long time, and productivity is heavilydecreased. Such problems can be remedied when a multi-layered wiringboard is formed by making interlayer connection by means of conductivepillars to be described afterward.

In addition, a plating step, that electrical connection among aplurality of wiring layers is made with through holes, has to make acomplex control to adjust a density of chemicals and a temperature.Besides, an apparatus for forming through holes and a facility forplating constitute a heavy burden in view of costs.

As described above, when the interlayer connection is made for themulti-layered wiring board using the through holes, productivity of thewiring substrate such as a printed wiring board (PWB) is decreased.Therefore, such a multi-layered wiring board is hard to comply with ademand for low cost.

To simplify the electrical connection among the wiring layers of themulti-layered wiring board, there is also proposed a method to connectthe wiring layers with the conductive pillars. This method formsconductive pillars, such as via lands, as interlayer connections formedon a wiring circuit, and inserts the conductive pillars into theinterlayer insulating layer such as a prepreg in its thickness directionto connect with the via lands formed on the opposed wiring layer.

The interlayer connection of the wiring circuit using the conductivepillars has advantages that a structure is simple, steps are not many,productivity is high, and high-density mounting can be made. However, aprinted wiring board having the interlayer connection of wiring circuitsusing the conductive pillars has disadvantages to be described asfollows.

The conductive pillars are formed on a conductive foil such as a copperfoil by screen printing a plurality of times using a mask. However, noapparatus was available to print those pillars automatically. In makingmultiple printings by the manpower, it is difficult to keep a fixed timeinterval between respective printing steps, and the conductive pillarsformed do not have uniform quality. Additionally an aspect ratio of theconductive pillars can be adjusted by the number of printing times, butmanagement of the number of times to print on very many conductive foilsbecomes a very large burden decrease a productivity.

FIG. 19A and FIG. 19B are diagrams schematically showing a step ofproducing a multi-layered wiring board using conventional conductivepillars, wherein an insulating resin layer is pierced by the conductivepillars which are formed on a conductive foil.

It is seen that a conductive foil 52 such as a copper foil havingconductive pillars 51 having a substantially conical shape is laminatedwith an insulating resin layer 53 such as a prepreg in a semi-curedstate (B-stage), then heated and pressed by a plane press to pierce theinsulating resin layer 53 by the conductive pillars 51. Referencenumerals 91 a, 91 b denote press plates of the plane press. To keep theshape of the conductive pillars 51, a releasing sheet 56 is placed onthe insulating resin layer 53.

However, the plane press is hard to press uniformly the entire area ofthe laminate. Therefore, all the conductive pillars 51 formed on theconductive foil 52 cannot pierce the insulating resin layer 53satisfactorily due to non-uniform pressing. The conductive pillars 51serve to make interconnection of the wiring layers of the multi-layeredwiring board, so that such defective piercing is directly related to afailure of the multi-layered wiring board.

To pierce the conductive pillars 51 by the plane press, it is necessaryto laminate the conductive foil 52, the insulating resin layer 53 andthe releasing sheet 56 in each pressing process. After pressing, thelaminate must be decomposed. Especially, when pressing is made manually,a long time is required to complete the process. Therefore, productivityof a wiring substrate is decreased.

Because of the drawbacks in the multi-layered wiring board having theinterlayer connection made by the conductive pillars, it is hard to putinto practical use.

Besides, when the conductive foil 52 and the insulating resin layer 53are laminated, there is a problem that the conductive foil is readilycontaminated by powder of the resin which forms the insulating resinlayer.

For example, a conventional apparatus for manufacturing a printed wiringboard which has the conductive foil 51 and the insulating resin layer 53laminated has a structure as shown in FIG. 20.

For example, the insulating resin layer 53 such as a prepreg set at apredetermined position is adsorbed by aspiration heads 93 andtransported so to be piled on the conductive foil 52 such as a Cu foilset at another predetermined position.

However, such a conventional apparatus has the following disadvantages.

The conventional aspiration heads partly hold the insulating resin layerby a point-to-point contact. Therefore, there is a problem that theinsulating resin layer has a wrinkle when it is held and the resinforming the insulating resin layer is partly powdered to disperse to thesurroundings. Furthermore, the powdered and dispersed portion of theinsulating resin such as a prepreg adheres to the surface of theconductive foil and the like. As a result, an etching failure is causedor a dent is formed due to irregularities formed by the resin adheredafter pressing.

In addition, the powdered prepreg produced in a step of cutting theprepreg adheres to the surface and end faces of the prepreg, and thepowder has a problem of causing the same disadvantages as describedabove.

SUMMARY OF THE INVENTION

The invention was completed to remedy the disadvantages described above.

Specifically, it is an object of the invention to provide an apparatusfor manufacturing a printed wiring board that conductive pillars can beformed automatically on a conductive foil. It is also an object of theinvention to provide an apparatus for manufacturing a printed wiringboard that conductive pillars having uniform properties can be formed ona conductive foil with high productivity.

The invention also aims to provide an apparatus for manufacturing amulti-layered wiring board with high productivity without havingdefective piercing. In addition, the invention aims to provide anapparatus for manufacturing a multi-layered wiring board that a laminatecontaining conductive pillars and an insulating resin layer can bepressed uniformly.

Besides, the invention aims to provide an apparatus for manufacturing aprinted wiring board that a powdered portion of the prepreg can beprevented from adhering.

In order to achieve the above-described objects, the apparatus and themethod for manufacturing a wiring board according to the invention hasthe following structure.

A first aspect of the invention relates to an apparatus formanufacturing a wiring substrate, which comprises a transporting meansfor transporting a sheet, the transporting means having a circuit wherethe sheet is circularly transported; a printing means for printing aconductive paste onto the sheet, the printing means being formed on thecircuit; a counting means for counting the number of times to print theconductive paste onto the sheet; and an ejecting means for ejecting thesheet from the circuit when the counted number reaches a preset number.

By configuring as described above, conductive pillars/bumps can beautomatically formed very accurately with high productivity.

The transporting means may have a conveyer combined with a directionchanger. Likewise, a transporting robot may be used to transport thesheet. Besides, the transporting means may further have a first dryingmeans on the circuit to dry the conductive paste printed by the printingmeans.

A memory may also be provided to store the set number for determiningthe number of printing times. The memory can be a non-volatilesemiconductor memory such as a NAND type flash memory or an AND typeflash memory.

The printing means preferably prints the conductive paste so to form asubstantially conical shape on the sheet. Thus, the conductive pillarshaving a substantially conical shape are formed on the sheet. Theconductive pillars having a substantially conical shape can easilypierce the insulating resin layer such as a prepreg in a semi-curedstate (B-stage). Accordingly, productivity of a multi-layered wiringsubstrate is improved.

The sheet on which the conductive pillars are printed can be aconductive sheet including a conductive foil such as a copper foil or analuminum foil. Such a conductive sheet may have a laminated structurecomprises at least one conductive layer and at least one insulatinglayer. The insulating layer can be a prepreg, a polyimide film, aceramics layer and the like. It is to be understood that the sheet onwhich the conductive pillars are printed may be a conductive layer or awiring layer exposed to the surface of a wiring substrate.

A second aspect of the invention relates to an apparatus formanufacturing a wiring substrate, which comprises a loading means forloading at least a sheet; a means for forming conductive pillars ontothe sheet; and a second drying means for drying the conductive pillarsformed on the sheet; wherein the means for forming the conductivepillars comprises a transporting means for transporting the sheet, thetransporting means having a first circuit and a second circuit where thesheet is circularly transported, the first circuit and the secondcircuit having a common part, a first printing means for printing aconductive paste on the sheet, the first printing means being formed onthe first circuit, a second printing means for printing the conductivepaste on the sheet, the second printing means being formed on the secondcircuit, a counting means for counting the number of times to print theconductive paste on the sheet, a first drying means for drying theconductive paste printed on the sheet, the first drying means beingformed on the common part of the first circuit and the second circuit, afirst distributing means for distributing the sheet loaded from theloading means to the first circuit and the second circuit, the firstdistributing means distributing the sheet ejected from the first dryingmeans to the first circuit and the second circuit, and a seconddistributing means for distributing the sheet ejected from the firstprinting means and the sheet ejected from the second printing means tothe first drying means when the counted number is less than the presetnumber of times, and the second distributing means distributing thesheet ejected from the first printing means and the sheet ejected fromthe second printing means to the second drying means when the countednumber reaches the preset number.

The first distributing means distributes the conductive sheet having theconductive paste printed by the first printing means to the firstcircuit, and the second distributing means distributes the conductivesheet having the conductive paste printed by the second printing meansto the second circuit.

In addition, the first printing means and the second printing means maybe disposed symmetrically to each other on the first circuit and thesecond circuit. For example, conductive foils to be a pair of conductivewiring layers to hold a single layered insulating resin layertherebetween can be formed simultaneously, and a throughput can beimproved.

In addition, the first printing means and the second printing meansrespectively print the conductive paste by using one identical mask whenthe conductive paste is printed onto the conductive paste alreadyprinted through the mask. Printing of the conductive paste using one andthe same mask prevents displacement and allows to form fine conductivepillars accurately and uniformly.

Furthermore, the apparatus for manufacturing a wiring substrate may alsohave a memory for holding the preset number of times of printing theconductive paste onto the sheet.

By configuring as described above, the apparatus for manufacturing awiring substrate according to the invention can form automatically theconductive pillars, which facilitate interlayer connection, with highproductivity and high accuracy. Especially, automation facilitates touniformly control the interval between respective printing steps, sothat the conductive pillars can be formed more uniformly. Accordingly,the conductive pillars have uniform properties, and the wiring substratehaving a large number of interlayer connections has improvedreliability.

An apparatus for manufacturing a printed wiring board according to theinvention, that an insulating resin layer is pierced by conductivepillars formed on a conductive foil, has the following structure.

Specifically, a third aspect of the invention relates to an apparatusfor manufacturing a wiring substrate, which comprises a pair of rollshaving a substantially parallel rotating axis, the rolls being held soas to form a gap therebetween; a means for loading a conductive sheethaving a first face where conductive pillars are formed, an insulatingresin sheet and a releasing sheet to the gap between the rolls so thatthe insulating resin sheet is interposed between the first face of theconductive sheet and the releasing sheet; and an adjusting means foradjusting the gap between the rolls so that the conductive pillarspierce the insulating resin sheet.

This pair of rolls is driven to rotate to allow the laminate to passthrough the rolls under pressure. Therefore, when one of the rollsrotates clockwise, the other roll rotates counterclockwise. Theapparatus for manufacturing a wiring substrate also has a driving meansfor driving the rolls so that the rolls have a rotating speedsynchronized with a loading speed.

The individual roll may have a hollow cylindrical structure. Thus, thegap between the pair of rolls can be prevented from becoming uneven dueto the expansion of rolls due to thermal expansion, and the laminate ofthe conductive foil, the insulating resin layer and the releasing sheetcan be pressed and heated more uniformly.

The respective rolls may have therein a heating means for heating sothat they have a uniform temperature distribution. For example, thedistribution of surface temperature of the rolls can be limited to asmall range by adjusting a winding density of a coil of an infraredheater for example. Therefore, the rolls are prevented from decentering,and the laminate can be heated and pressed more uniformly.

In addition, the releasing sheet may be loaded into the gap between thepair of rolls so that the releasing sheet has a substantially constanttension. By loading the releasing sheet into the gap between the rollswhile adjusting to have a uniform tension, the releasing sheet can beprevented from having a wrinkle during pressing. Therefore, the laminatecan be pressed under uniform pressure.

Furthermore, the conductive foil may be loaded so to run along one ofthe rolls. By adjusting the loading angle so to increase a contact areabetween the conductive foil and one of the rolls, the laminate is heatedpreliminarily before being pressed between the rolls. Thus, theinsulating resin layer is pierced by the conductive pillars moreuniformly and smoothly.

A fourth aspect of the invention relates to a method for manufacturing awiring substrate, which comprises steps of loading a conductive sheethaving a first face where conductive pillars are formed, an insulatingresin sheet and a releasing sheet to a gap of a pair of rolls having asubstantially parallel rotating axis so that the insulating resin sheetis interposed between the first face of the conductive sheet and thereleasing sheet; and adjusting the gap between the rolls so that theconductive pillars pierce the insulating resin sheet.

Specifically, the method for manufacturing a printed wiring boardaccording to the invention laminates the sheet such as a conductive foilhaving the conductive pillars in a substantially conical shape formed onthe first face with the insulating resin sheet in a semi-cured state,and loads the laminate into the gap between the pair of rotating rollsto pierce the insulating resin sheet by the conductive pillars. Theinvention relates to the apparatus for manufacturing a printed wiringboard that the conductive paste is printed on the conductive foil toform the conductive pillars, the insulating resin layer is laminated onthe conductive foil, the laminate is heated and pressed to pierce theconductive pillars into the synthetic resin sheet, another conductivemetallic foil is overlaid thereon, heated and pressed to make electricalconnection of the upper and lower conductive metallic foils, and canapply the step of piercing the conductive pillars into the syntheticresin sheet to a material having a different thickness and improve ayield by varying the two rolls, the conductive bump piercing assistingmaterial and the main material loading angle.

The apparatus for manufacturing a printed wiring board according to theinvention, that the conductive foil and the insulating resin layer arelaminated, has the following structure.

A fifth aspect of the invention relates to an apparatus formanufacturing a wring substrate, which comprises a holding means havinga planer surface for holding an insulating resin sheet having a firstface and a second face, the holding means aspirates the first face ofthe insulating resin sheet on the plane surface; a housing for storing aconductive foil, the housing having an opening for introducing theholding means holding the insulating resin sheet; a transporting meansfor transporting the holding means into the housing through the opening,the transporting means piling the insulating resin sheet onto theconductive foil; and an adjusting means for adjusting a pressure insidethe housing so that the pressure inside the housing is higher than apressure outside the housing.

Furthermore, the apparatus for manufacturing a wring substrate may havea cleaning means, which is formed outside of the opening of the housingand cleans the surface of the prepreg adsorbed by the holding member andits opposite surface. In addition, the cleaning means having at least anaspirating slit elongated with the opening, for example.

Furthermore, the apparatus for manufacturing a wring substrate may havea cleaning means, which is formed outside of the opening of the housingand cleans the surface of the prepreg adsorbed by the holding member andits opposite surface.

By configuring as described above, the apparatus for manufacturing awiring substrate according to the invention can hold the resin sheetsuch as a prepreg without causing a wrinkle. In addition, no powderedresin is dispersed to the surroundings, so that a failure due to thedispersed powder can be decreased during laminating.

According to the present invention, productivity of a wiring substratecan be improved substantially, and reliability of a wiring substrate canbe improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing the configuration of anapparatus for manufacturing a printed wiring board according to theinvention;

FIG. 2 is a diagram schematically showing an exemplified processing flowof the apparatus for manufacturing the printed wiring board of theinvention shown in FIG. 1;

FIG. 3 is a diagram schematically showing an exemplified configurationof a control system of the apparatus for manufacturing the printedwiring board of the invention shown in FIG. 1;

FIG. 4A and FIG. 4B are diagrams schematically showing a process toprint a conductive paste on a conductive foil by a printing means;

FIG. 5A, FIG. 5B and FIG. 5C are diagrams schematically showing a statethat conductive pillars are formed on a conductive foil by printing aconductive paste thereon a plurality of times;

FIG. 6 is a diagram showing an exemplified configuration of theapparatus for manufacturing a printed wiring board of the invention,which has a drying means disposed on a circuit of a transporting means;

FIG. 7 is a diagram schematically showing another exemplifiedconfiguration of the apparatus for manufacturing a printed wiring boardaccording to the invention;

FIG. 8 is a diagram schematically showing a more specific configurationof the apparatus for manufacturing a printed wiring board according tothe invention shown in FIG. 7;

FIG. 9 is a perspective view schematically showing an exemplifiedconfiguration of the apparatus for manufacturing a printed wiring boardaccording to the invention;

FIG. 10A and FIG. 10B are side and top views schematically showing theapparatus for manufacturing a printed wiring board of the inventionshown in FIG. 9;

FIG. 11A and FIG. 11B are diagrams schematically showing the structureof a pair of rolls for pressing a laminate in the apparatus formanufacturing a printed wiring board according to the invention;

FIG. 12A is a diagram showing the distribution of a surface temperatureof rotating rolls with their inside coil kept to have a fixed windingdensity;

FIG. 12B is a diagram showing the distribution of a surface temperatureof rotating rolls with their inside coil adjusted to have a windingdensity small at the middle and large at both ends;

FIG. 13 is a diagram schematically showing an exemplified structure of aloading roll for a releasing sheet disposed in the apparatus formanufacturing a printed wiring board according to the invention;

FIG. 14 is a graph schematically showing a change in tension of areleasing sheet running between first and second rolls with or without aloading roll which can adjust the tension of the releasing sheet;

FIG. 15 is a diagram schematically showing another exemplified structureof the apparatus for manufacturing a printed wiring board according tothe invention;

FIG. 16 is an enlarged diagram schematically showing the first andsecond rolls of the apparatus for manufacturing a printed wiring boardaccording to the invention shown in FIG. 15;

FIG. 17 is a diagram schematically showing an exemplified structure ofthe apparatus for manufacturing a printed wiring board according to theinvention;

FIG. 18 is a diagram schematically showing an exemplified structure of aholding means having a plane adsorbing surface;

FIG. 19A and FIG. 19B are diagrams schematically showing a step ofproducing a multi-layered wiring board using conventional conductivepillars; and

FIG. 20 is a diagram schematically showing an exemplified structure ofthe apparatus for manufacturing a conventional printed wiring boardhaving a conductive foil and an insulating resin layer laminated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will be described in further detail with reference to theaccompanying drawings.

EMBODIMENT 1

FIG. 1 is a diagram schematically showing a structure of the apparatusfor manufacturing a printed wiring board according to the invention.This apparatus for manufacturing a printed wiring board comprises atransporting means 11 having a circuit to circularly transport a sheet,a printing means 12 for printing a conductive paste onto the sheet, andan ejecting means 13 for ejecting the sheet from the circuit when thecounted number of times to print the conductive paste onto the sheet hasreached a preset number. As the ejecting means, a distributor can beemployed. The distributor distributes the printed sheet out of thecircuit when the counted number of times to print the conductive pasteonto the sheet has reached a preset number. The distributor alsodistributes the printed sheet to the circuit circularly when the countednumber of times is less than a preset number.

The circularly loading of the sheet and the discharge may bedistinguished by, for example, a distributing means having a counter 21to be described afterward.

The printing means 12 includes, for example, a screen printing machineand the like. Specifically, a conductive paste may be printed through amask having pits formed at predetermined positions on a loadedconductive foil or a conductive foil on which a conductive paste hasbeen printed by the printing means 12.

The transporting means 11 may consist of a combination of a conveyer fortransporting a conductive foil ejected from the printing means, adirection-changer for changing a transporting direction, an automaticcharging machine for loading a conductive foil into the printing meansand the like as required. As a part of the transporting means 11, anautomatic loader and an automatic ejector can be disposed for loading toand ejecting from the printing machine, so that the conductive paste canbe printed automatically onto the conductive foil circulating along theroute of the transporting means 11.

The conductive foil on which the conductive paste is printed iscircularly supplied to the same printing means by the transporting means11.

On the other hand, when the number of times to print the conductivepaste onto the previously printed conductive paste reaches a presetnumber, the conductive foil is ejected from the transporting means 11 bythe ejecting means 13.

The ejecting means 13 may comprise a combination of, for example, amemory 23 having the number of printing times preset and a counter 21for counting the number of printing times. For example, the countednumber by the counter is compared with the preset number in the memoryto judge whether the conductive paste-printed conductive foil shall becirculated along the circuit to print additionally the conductive pasteor ejected from the transporting means. The preset number of printingtimes may be a value fixed on the apparatus or may be input through aninput means by an operator.

FIG. 2 is a diagram schematically showing an exemplified process by acontrol system of the apparatus for manufacturing the printed wiringboard according to the invention shown in FIG. 1. FIG. 3 is a diagramschematically showing an exemplified configuration of a control systemof the apparatus for manufacturing the printed wiring board according tothe invention shown in FIG. 1.

The number of printing times C is counted by the counter every time theconductive paste is printed by the printing means, such as a screenprinter and compared with a predetermined value S in a nonvolatilememory such as a NAND flush type EEPROM 23 by a CPU 22. When the countednumber C is less than the predetermined value S, the conductive foil iscirculated to be introduced repeatedly into the printing means. When thecounted number C becomes equal to the predetermined value S, theconductive foil is ejected from the transporting means and not printedwith the conductive paste any more. On the circuit of the transportingmeans 11 is disposed a first drying means different from a drying oven(second drying means) in a subsequent step.

FIG. 4A and FIG. 4B are diagrams schematically showing a process toprint a conductive paste on a conductive foil by a printing means.

Conductive pillars 14 can be formed by screen printing a conductivepaste 18 onto a conductive foil 17 through a metal screen 16 which haspits 15 formed corresponding to positions where the conductive pillars14 are formed.

The conductive paste 18 is spread with a squeegee 19 so to fill the pits15, and the metal mask 16 is lifted up to form the conductive pillars 14having a substantially conical shape on the conductive foil 17 (see FIG.4A, FIG. 4B). To increase an aspect ratio of the conductive bump 14,namely to increase a ratio (=(diameter of the bottom of the conductivebump/height of the conductive bump)), the conductive paste 18 may beprinted a plurality of times so to print the conductive paste over thepreviously printed conductive paste 18.

FIG. 5A, FIG. 5B and FIG. 5C are diagrams schematically showing a statethat the conductive pillars are formed on the conductive foil 17 byprinting the conductive paste 18 thereon a plurality of times. FIG. 5A,FIG. 5B and FIG. 5C show the conductive pillars which were formed byprinting the conductive paste one time, two times and three times,respectively.

To print the conductive paste a plurality of times, one and the samemask is preferably used to uniformly form all conductive pillars and toprevent displacement. The printed conductive paste may be driedtemporarily before printing the conductive paste additionally.

In the apparatus for manufacturing a printed wiring board according tothe invention, the conductive foil is circulated to the same printingmeans by means of the transporting means, so that the same mask can beused to print the conductive paste. Accordingly, printing displacementcan be minimized, and many conductive pillars can be formed uniformly onthe conductive foil. This promotes a reliability and a productivity ofthe printed wiring board.

As described above, the apparatus for manufacturing a printed wiringboard according to the invention prints the conductive paste on theconductive foil through one and the same mask a plurality of times toform the conductive pillars and has the transporting means to reload theconductive foil ejected from the printing means to the same printingmeans.

The predetermined route of the transporting means containing theprinting means may also have a drying means such as a drying oven forpreliminarily drying the printed conductive paste

FIG. 6 is a diagram showing an exemplified configuration of theapparatus for manufacturing a printed wiring board according to theinvention, which has a drying means disposed on the circuit of theconveying means.

This manufacturing device has the printing means 12, the ejecting means13 and a drying means 20 for preliminarily drying the conductive pasteon the circuit of the conveying means 11, and repeats to print and dryuntil the number of printing times of the conductive paste reaches apredetermined value. The configuration shown in FIG. 6 has the ejectingmeans 13 disposed downstream of the printing means and upstream of thedrying means. Therefore, the conductive foil on which the last printingwas completed does not pass through the drying means 20 but ejected fromthe transporting means. The ejected conductive foil is introduced into,for example, a main drying oven (second drying means) and dried morethan in the preliminary drying.

Thus, the conductive paste printed on the conductive foil is dried bythe preliminary drying means (first drying means). By repeating theaforementioned process for the predetermined number of times, theconductive pillars having a high aspect ratio (a diameter-to-heightratio of the bottom of the conductive bump) can be formed. The apparatusfor manufacturing a printed wiring board according to the invention cancontrol the factors, such as the number of printing times, preliminarydrying duration and transporting duration, which affect on the qualityof the conductive pillars. Thus, a printed wiring board having uniformproperties and high reliability can be produced. In addition, by keepinga fixed interval between the printing steps, the conductive pillars canbe formed to have uniform quality.

The apparatus for manufacturing a printed wiring board according to theinvention does not adopt a method to print the conductive paste on theconductive foil by a plurality of printing means but circulates theconductive foil to one and the same printing means, so that machinecosts can be reduced and the same mask can be used to print a pluralityof times. Since the same mask is used to print the required multiplenumber of times to form the conductive pillars, displacement can beminimized and the conductive pillars can have high quality. Therefore,reliability of the interlayer connection of a multi-layered wiring boardcan be improved.

EMBODIMENT 2

FIG. 7 is a diagram schematically showing another exemplifiedconfiguration of the apparatus for manufacturing a printed wiring boardaccording to the invention.

This apparatus for manufacturing a printed wiring board has twotransporting means 11 a, 11 b symmetrically disposed in parallel to eachother. The transporting means 11 a, 11 b have printing means 12 a, 12 brespectively.

The manufacturing device shown in FIG. 7 has a heating means 20 which iscommonly used by the two transporting means 11 a, 11 b. The common useof the heating means 20 improves productivity because a tact timerequired for the preliminary heating is relatively short.

FIG. 8 is a diagram schematically showing a more specific configurationof the apparatus for manufacturing a printed wiring board according tothe invention shown in FIG. 7.

The conductive foil such as a copper foil is first delivered to thefirst circulation system (circuit) 11 a and the second circulationsystem (circuit) 11 b by a distributing type direction changer 31.

The divided conductive foils are transported by stock conveyers 32 a, 32b into conductive foil loading devices 33 a, 33 b.

The conductive foil loading devices 33 a, 33 b introduce the conductivefoils into printing machines 12 a, 12 b. The printing machines 12 a, 12b print the conductive paste on predetermined positions of theintroduced conductive foils through the above-described metal mask bythe screen printing.

The conductive foils ejected from the printing machines 12 a, 12 b aretransported by discharge transporting machines 34 a, 34 b, theirtransporting directions are changed by direction changers 35 a, 35 b,and they are introduced into the ejecting means 13 by conveyers 36 a, 36b. The ejecting means may be, for example, a distributing type directionchanger or the like.

As described above, the ejecting means 13 compares the number ofprinting times, namely the number of times that the conductive foil hascirculated the first and second circulation systems 11 a, 11 b, with thepredetermined number of printing times in order to judge whether theconductive foil shall be remained in or ejected from the circulationsystem.

The number of printing times is counted by a counter which is mounted onthe printing machines 12 a, 12 b or at a midpoint of the circuit.

Furthermore, the number of times that the conductive paste is printed ona single conductive foil may be determined in advance, or a means intowhich the determined number of printing times can be input may beprovided. The number of times to print the conductive paste to form theconductive pillars on the conductive foil may be determined based onphysical properties such as a viscosity and thixotropy of the conductivepaste, processing conditions such as a processing temperature and adesired shape of conductive pillars.

It is assumed that twenty conductive foils are loaded in thedistributing type direction changer 31 at one time, and the number oftimes to print the conductive paste is set three. The distributing typedirection changer 31 divides the twenty conductive foils into two eachhaving ten conductive foils and introduces them into the first andsecond circulation systems 11 a, 11 b, respectively. Each group of tenconductive foils undergone the first printing is not ejected by theejecting means but introduced into the drying oven 20 and dried at about80 to about 150° C. for about 30 seconds. At the time, the heatingconditions may be controlled by adjusting a temperature of the dryingoven 20 and duration for passing through the drying oven 20. Asdescribed above, the apparatus for manufacturing a printed wiring boardaccording to the invention has a relatively short tact time for theprinted conductive paste. Therefore, the drying oven 20 is shared by thetwo circulation systems 11 a, 11 b. As a result, an area for installingthe drying oven can be decreased and the cost for its installation canbe reduced. Besides, a volume-to-surface area ratio of the drying ovencan be decreased, and stable heating can be made efficiently. After thethird heating, the conductive foils are ejected from the circuit by theejecting means. In this configuration, the ejected conductive foils areintroduced into the main drying oven (second drying means) and dried ata temperature higher than in the preliminary heating oven.

The apparatus for manufacturing a printed wiring board according to theinvention shown in FIG. 7 and FIG. 8 has a plurality of circulationsystems, thereby improving throughput. In addition, a double-sidecopper-clad substrate is produced by intervening a single insulatingresin layer (prepreg) between two conductive foils having conductivepillars. The apparatus for manufacturing a printed wiring boardaccording to the invention can also produce a plurality of conductivefoils having a single layered insulating resin layer therebetweensimultaneously.

Thus, the apparatus for manufacturing a printed wiring board accordingto the invention is capable of promoting stability and productivity toproducing a printed wiring board having interlayer connection by meansof the conductive pillars suitable for high-density mounting. Theapparatus for manufacturing a printed wiring board according to theinvention is capable of maintaining duration punctual and flat forperforming the printing and preliminary drying steps and transportation.Therefore, a large number of conductive pillars can be formed uniformlyon a single conductive foil. Thus, a reliability of the printed wiringboard is promoted.

EMBODIMENT 3

FIG. 9 is a perspective view schematically showing an exemplifiedconfiguration of the apparatus for manufacturing a printed wiring boardaccording to the invention. FIG. 10A and FIG. 10B are side and top viewsschematically showing the apparatus for manufacturing a printed wiringboard according to the invention shown in FIG. 9.

This apparatus for manufacturing a printed wiring board passes alaminate of a conductive foil having conductive pillars and aninsulating resin layer such as a prepreg through the gap between tworolls to pierce the insulating resin layer by the conductive pillars.

Specifically, the apparatus for manufacturing a printed wiring boardlaminates a conductive foil 52 having conductive pillars 51 in asubstantially conical shape on its first face and a semi-curedinsulating resin layer 53 to pierce the insulating resin layer 53 by theconductive pillars 51. This apparatus comprises a first roll 54; asecond roll 55 disposed in parallel with the first roll 54 with apredetermined gap therebetween; a means for loading the conductive foil52, the insulating resin layer 53 and a releasing sheet 56 to passthrough the gap between the first roll 54 and the second roll 55 so thatthe insulating resin layer 53 is interposed between the face of theconductive foil 52 having the conductive pillars 51 and the releasingsheet 56; a driving means for driving the first roll 54 and the secondroll 55 so that the first roll 54 and the second roll 55 have a rotatingspeed synchronized with the loading speeds of the conductive foil 52,the insulating resin layer 53 and the releasing sheet 56 loaded to passthrough the gap between these rolls; and an adjusting means foradjusting the gap between the first roll 54 and the second roll 55 sothat the conductive pillars 51 pierce the insulating resin layer 53. Thefirst roll 54 and the second roll 55 have a heating means such as anelectric heater in them to heat the laminate so that the conductivepillars are easy to pierce the insulating resin layer. Reference numeral63 denotes transporting rolls for transporting the conductive foil 52and the insulating resin layer 53.

The releasing sheet 56 serves to prevent the pierced conductive pillars51 from being crushed. The releasing sheet 56 is loaded by a releasingsheet loading roll 57, passed through the gap between the first roll 54and the second roll 55, separated from the laminate of the conductivefoil and the insulating resin layer and wound around a releasing sheetwinding roll 58. The releasing sheet 56 is always loaded into the gapbetween the two rolls 54, 55.

The releasing sheet 56 has its loading angle adjusted by a guide roll 59before passing through the gap between the first roll 54 and the secondroll 55. The guide roll 59 may be adjustable so that a tension of thereleasing sheet loaded into the gap between the first roll 54 and thesecond roll 55 is made constant. Furthermore, a guide roll 60 providesthe releasing sheet 56 with a given tension required when it isseparated from the laminate of the conductive foil 52 and the insulatingresin layer 53.

The first roll 54 and the second roll 55 are held to have a parallelrotating axis and driven to rotate in synchronization with the loadingspeed of the laminate consisting of the conductive foil 52, theinsulating resin layer 53 and the releasing sheet 56 loaded into the gapbetween these rolls. Driving to rotate in synchronization means that thefirst and second rolls 54, 55 are driven so that a speed that thelaminate passes through the gap between the first roll 54 and the secondroll 55 is substantially equal to a rotating speed in a tangentdirection on the surface of the first roll 54 and the second roll 55.

The laminate of the conductive foil 52 having the conductive pillars 51,the insulating resin layer 53 and the releasing sheet 56, which isloaded into the gap between the first roll 54 and the second roll 55, ispressed and heated by these rolls, so that the conductive pillars 51pierce the insulating resin layer 53. A pressing force may be adjustedby adjusting the gap between the two rolls. The apparatus formanufacturing a printed wiring board according to the invention appliesa pressing force with the releasing sheet 56 also laminated.Accordingly, the conductive pillars 51 having pierced the insulatingresin layer 53 can keep their shapes as they are.

As described above, the conventional plane pressing method places andpresses the conductive foil having the conductive pillars, theinsulating resin layer and the releasing sheet as a pierce assistingmaterial on the plane heat plate of the press as shown in FIG. 19A.However, it is hard to press to apply a uniform pressure onto all partsof the layers. For example, all the conductive pillars were hard topierce the insulating resin layer due to the occurrence of nonuniformpressing as shown in FIG. 19B.

The apparatus for manufacturing a printed wiring board according to theinvention presses the conductive foil 52 and the insulating resin layer53 through the releasing sheet 56 by a linear pressing area formed inthe gap between the first roll 54 and the second roll 55. Thus, moreuniform pressing can be made as compared with the conventional planepress. In addition, the conductive pillars 51 can uniformly pierce theinsulating resin layer.

Furthermore, the apparatus for manufacturing a printed wiring board isstructured so that a plurality of laminates can be pressed continuously.Therefore, productivity of the piercing step that the insulating resinlayer 53 is pierced by the conductive pillars 51 can be improvedremarkably. In addition, the releasing sheet 56 which is used as thepierce assisting material can be separated automatically. Therefore, theconductive pillars can pierce without fail, a lead time can be shortenedextensively, and productivity can be improved remarkably.

EMBODIMENT 4

FIG. 11A and FIG. 11B are diagrams schematically showing the structureof a pair of rolls for pressing a laminate in the apparatus formanufacturing a printed wiring board according to the invention.

The first roll 54 and the second roll 55 serve to press and also heatthe laminate. The laminate is heated at a temperature in a range ofabout 100 to about 160° C. so that the insulating resin layer issoftened but not hardened. If the rolls had a solid inside (FIG. 11A),the midpoint of the rolls is largely swelled and decentered due to heatapplied by the heater or the like. In addition, if decentered, the gapbetween the first roll 54 and the second roll 55 may have narrow andwide parts. Therefore, both ends of the laminate are not pressedsufficiently, and the pierced condition becomes often unsatisfactory.

In view of above, in order to prevent decentering from occurring due toheating, the apparatus for manufacturing a printed wiring boardaccording to the invention preferably adopts a hollow-structured rollfor the first and second rolls.

FIG. 11B is a diagram schematically showing the structure of the firstroll 54 and the second roll 55.

In this case, the first roll 54 and the second roll 55 have a hollowstructure so that the laminate of the conductive foil 52, the insulatingresin layer 53 and the releasing sheet 56 can be pressed and heateduniformly and accurately by the first roll 54 and the second roll 55.The rolls are made of iron, stainless steel or the like, and have awidth of about 400 to about 500 mm and a diameter of about 80 to about100 mm. The rolls also have a thickness d of about 10 mm and a rotatingshaft with a diameter of about 30 mm.

The gap between the first roll and the second roll can be adjusted by anadjusting means 61 which is integrally formed with the driving means fordriving the rolls.

Therefore, the first roll 54 and the second roll 55 swell and shrinkuniformly as the whole, so that the gap size can be held uniform alongthe rolls. Thus, all the conductive pillars can pierce the insulatingresin layer by finely adjusting the gap size between the first roll 54and the second roll 55.

The apparatus for manufacturing a printed wiring board according to theinvention has an infrared heater within the first roll 54 and the secondroll 55 as the heating means for heating them. Furthermore, a coil 62configuring the infrared heater has a winding density small at thecenter and large at the ends so that a difference between a temperatureTc at the center of the roll and a temperature Te at the end is small.

FIG. 12A and FIG. 12B are diagrams showing the distribution of a surfacetemperature of the roll with the winding density of the coil 62 in theroll kept constant (FIG. 12A) and with the winding density small at themiddle and large at both ends (FIG. 12B).

When the winding density of the coil is kept uniform, the roll surfacehas a surface temperature Tc at the center higher than a temperature Teat the ends. However, it is seen that the surface temperature of theroll is uniform and Tc and Te are substantially equal by adjusting thewinding density of the coil 62.

As described above, the first roll 54 and the second roll 55 can beprevented from decentering by optimizing the arrangement of the heatingmeans for heating them. Besides, the first roll 54 and the second roll55 have a more uniform surface temperature, and the conductive pillarscan pierce the insulating resin layer more uniformly. Therefore, aprinted wiring board can be manufactured to have uniform properties andhigh reliability.

EMBODIMENT 5

The inventors have found that a tension of the releasing sheet is verysignificant as one of conditions to pierce by all the conductive pillarsfinely. According to a type of printed wiring board to be manufactured,the conductive pillars may have various heights and diameters.Accordingly, the releasing sheet is required to have its thickness andmaterial varied according to the shape of the conductive pillars. Inaddition, a tension of the releasing sheet is also required to beadjusted according to what releasing sheet is used. If the releasingsheet 56 had a wrinkle, the conductive foil 51 and the insulating resinlayer can not be pressed uniformly.

FIG. 13 is a diagram schematically showing an exemplified structure ofthe loading roll 57 for the releasing sheet disposed in the apparatusfor manufacturing a printed wiring board according to the invention.

The apparatus for manufacturing a printed wiring board according to theinvention shown in FIG. 9 needs to rotate the winding roll 58 fasterthan the loading roll 57 for the releasing roll 56. In addition, it isnecessary to cushion a change in tension as the rolls have a varyingdiameter.

The loading roll 57 shown in FIG. 13 can be pushed from both ends of therotating axis by means of springs 71 and screws 72. In addition, asliding plate 73 made of polyvinylidene fluoride or the like and havinga small friction is inserted so to enable continuous and smooth loadingof the releasing sheet 56. When a given force is applied from both endsof the shaft, the loading roll 57 rotates to follow the rotation of therotating axis, so that the releasing sheet is loaded while keeping thepredetermined tension of the releasing sheet. Therefore, even if a largeforce is applied instantaneously, a tension of the releasing sheet 56between the first roll 54 and the second roll 55 can be kept at acertain level.

FIG. 14 is a graph schematically showing a change in tension of thereleasing sheet running between the first and second rolls with orwithout the loading roll which can adjust the tension of the releasingsheet as shown in FIG. 13. Thus, a change in tension of the releasingsheet can be made small by having the tension adjusting means as shownin FIG. 13.

Furthermore, the tension of the releasing sheet may be adjusted bymaking the guide roll 59 variable so to adjust its position.

By configuring as described above, the releasing sheet 56 can be loadedstably while keeping a predetermined tension according to the shape andsize of the bumps. Therefore, piercing by the conductive pillars can bemade stably even if the conductive pillars are small in size or theinsulating resin layer has a small thickness.

EMBODIMENT 6

FIG. 15 is a diagram schematically showing another exemplified structureof the apparatus for manufacturing a printed wiring board according tothe invention. FIG. 16 is an enlarged diagram schematically showing thefirst and second rolls of the apparatus for manufacturing a printedwiring board according to the invention shown in FIG. 15.

This apparatus for manufacturing a printed wiring board has a loadingangle of the laminate of the conductive foil 52 having the conductivepillars 51 and the insulating resin layer 53 such as a prepreg in asemi-cured state shifted so to run along the second roll 55 with respectto the gap between the first roll 54 and the second roll 55.

The loading angle of the laminate of the conductive foil 52 and theinsulating resin layer 53 to the gap between the first roll 54 and thesecond roll 55 may be adjusted by guide rolls 64 a, 64 b. At this time,the laminate is preferably loaded under adjustment so that a directionof the force applied to the conductive pillars formed on the conductivefoil 52 becomes as equal as possible to the axial direction of theconductive pillars, namely a normal direction of the conductive foil.Accordingly, even if the conductive pillars in a substantially conicalshape have a high aspect ratio, the conductive pillars can be preventedfrom separating from the conductive foil or deforming.

Besides, the guide rolls 64 a, 64 b can be made variable to adjust theloading angle to the gap between the two rolls, so that various types ofprinted wiring boards having various sizes of the conductive pillars 51can be produced, and the insulating resin layer 53 can be pierceduniformly regardless of the size and shape of the conductive pillars 51.

In addition, the loading angle of the laminate can be shifted so to tunalong the second roll 55 to enable the enlargement of a contact area ofthe laminate with the second roll 55. Therefore, before passing throughthe gap between the first roll and the second roll, the laminate of theconductive foil 52 and the insulating resin layer 53 can be heatedpreliminarily by the second roll, the conductive pillars can pierce theinsulating resin layer 53 more uniformly and smoothly, a printed wiringboard to be manufactured has improved quality, and productivity can beimproved.

EMBODIMENT 7

FIG. 17 is a diagram schematically showing an exemplified structure ofthe apparatus for manufacturing a printed wiring board according to theinvention.

This apparatus for manufacturing a printed wiring board is an apparatusfor laminating the conductive foil and the insulating resin sheet suchas a prepreg and comprises a holding means 82 having a plane adsorbingsurface 81 for holding an insulating resin sheet 53; a housing 84 forstoring the conductive foil 52 and having side walls; a means 85 forloading the holding means 82 holding the insulating resin sheet 53 intothe housing 84 through an opening 83 and overlaying the insulating resinsheet 53 onto the conductive foil 52; a pressure adjusting means 86 foradjusting a pressure inside the housing 84 so to make it higher than apressure outside the housing; and a cleaning means 87 for cleaning thesurface of the insulating resin sheet 53 adsorbed by the holding means82 and its opposite surface.

FIG. 18 is a diagram schematically showing an exemplified structure ofthe holding means 82 having a plane adsorbing surface 81. The adsorbingsurface 81 has a large number of suction holes 89 and its oppositesurface is under a reduced pressure. The holes formed on the adsorbingsurface 81 are required to be formed so to hold the insulating resinsheet 53 such as a prepreg in a flat state. If the insulating resinsheet 53 has a wrinkle, a powdered portion of the resin is dispersedfrom the wrinkled part to contaminate the circumference. The adsorbingsurface 81 may be, for example, a stainless steel plate with very fineholes formed in a large number or may be formed of a porous material.

The housing 84 is a space for holding the insulating resin sheet 53loaded by the holding means 82 and the conductive foil 52 on which theinsulating resin sheet 53 is laminated. The housing 84 is adjusted tohave a pressure higher than outside the housing 84, so that the powderedportion of the prepreg and the like can be prevented from entering intothe housing 84 from outside.

The housing 84 has the opening 83 through which the holding means 82holding the insulating resin sheet 53 enters. The opening 83 may beformed to suit the size and shape of the holding means 82.

In addition, openings 88 a, 88 b are formed at a lower part of opposedside walls of the housing. The opening 88 a is used to enter theconductive foil into the housing, and the opening 88 b ejects thelaminate of the conductive foil and the insulating resin sheet. Thelaminate ejected through the opening 88 b may be introduced into theapparatus for manufacturing a printed wiring board according to theinvention shown in, e.g. FIG. 9 or FIG. 15.

The cleaning means 87 for cleaning the surface of the insulating resinsheet 53 adsorbed by the holding member and its opposite surface isformed adjacent to the opening 83 and outside of the housing 84. Thecleaning means 87 may be, for example, a vacuum suction apparatus. Inthis case, the cleaning means 87 must have a suction force smaller thanthe adsorbing force of the holding means 82.

The apparatus for manufacturing a printed wiring board according to theinvention shown in FIG. 18 holds the holding means 82, the adsorbingsurface 81, the housing 84, the cleaning means 87 and the like at aground potential so to prevent from adsorbing the powdered portion ofthe prepreg due to electrification caused by friction or the like.

Operation of the apparatus for manufacturing a printed wiring boardconfigured as described above will be described.

First, the holding means 82 adsorbs to hold the insulating resin sheet53 stocked in a predetermined place.

Meanwhile, the conductive foil 52 having, for example, the conductivepillars 51 formed is loaded into the housing 84, which is kept to have apressure higher than the circumference, through the opening 88 a.

The holding means 82 holding the insulating resin sheet 53 by its flatadsorbing surface 81 is introduced by a transporting means (not shown)into the housing 84 through its opening 83. At this time, the surfaceopposite from the surface of the insulating resin sheet 53 held by theadsorbing surface 81 is cleaned by the cleaning means 87 such as avacuum suction apparatus disposed outside of the opening 83 of thehousing 84 to remove dust such as the powdered portion of the resin.Since the holding means 82, the adsorbing surface 81, the housing 84,the cleaning means 87 and the like are held at a ground potential,contamination such as the powdered portion of the resin can be removedeffectively.

The insulating resin sheet introduced into the housing 84 is aligned andlaminated with the conductive foil 52. After laminating, the aspirationby the holding means is released, and the laminate of the conductivefoil 52 and the insulating resin sheet 53 is ejected through the opening88 b and introduced into the apparatus for manufacturing a printedwiring board according to the invention as shown in FIG. 9 and FIG. 15,wherein the conductive pillars 51 formed on the conductive foil piercethe insulating resin sheet 53.

Furthermore, the place where the insulating resin sheets are stored mayhave a space similar to the housing 84 in order to prevent the powderedportion of the resin and the like configuring the insulating resin sheetfrom dispersing to the surroundings.

By configuring as described above, the apparatus for manufacturing aprinted wiring board according to the invention can decrease extensivelythe powdered portion of the insulating resin such as a prepreg fromadhering to the surface of the conductive foil such as a copper foil.Therefore, defective etching due to the adhesion of the powdered resinand dents can be prevented from occurring, quality of a printed wiringboard can be improved, and productivity can also be improved.

The apparatus for manufacturing a printed wiring board according to theinvention can easily produce stably a printed wiring board havinginterlayer connection by the conductive pillars suitable forhigh-density mounting. The apparatus for manufacturing a printed wiringboard according to the invention can perform the respective printingsteps, the preliminary drying step and transportation in a fixedduration. Therefore, a large number of conductive pillars can be formeduniformly on a single conductive foil. In addition, a very reliableprinted wiring board can be produced.

As compared with the conventional press using two parallel flat plates,a uniform pressure can be applied to pierce the insulating resin layerby the conductive bumpers formed on the conductive foil. Therefore,nonuniform pressurization can be prevented, and a yield can be improved.Besides, the time required in setting and disassembling the laminate canbe reduced extensively thanks to the continuous processing, andproductivity can be improved.

Furthermore, since the two rolls have a hollow cylindrical structure andthe distribution of temperature on the rolls is prevented from becomingnonuniform by the heating means, the rolls are prevented fromdecentering due to thermal expansion, and the application of pressurecan be made uniformly while heating.

The releasing sheet as the pierce assisting material for the conductivepillars can be supplied and wound continuously by the rolls, so thatproductivity can be improved remarkably. Furthermore, a tension of thereleasing sheet can be adjusted to prevent the releasing sheet fromhaving a wrinkle while pressing by the two rolls, and the laminate canbe pressed more uniformly.

Furthermore, a loading angle of the laminate of the conductive foil andthe insulating resin layer to the gap between the two rolls can beshifted to have a large contact area with the rolls, so that thelaminate can be heated preliminarily before pressing, and the insulatingresin layer can be pierced by the conductive pillars uniformly andsmoothly. In addition, when the insulating resin layer is pierced by theconductive pillars having a small diameter which have a low adhesivestrength against the conductive foil, the conductive pillars can beprevented from being separated due to a force laterally applied thereto.

Besides, the apparatus for manufacturing a printed wiring boardaccording to the invention to laminate the conductive foil and theinsulating resin layer can substantially reduce the adhesion of thepowdered portion of the insulating resin such as a prepreg to thesurface of the conductive foil such as a copper foil. Therefore,defective etching and a dent due to the adhesion of the powdered portionof the resin can be prevented, so that quality of a printed wiring boardcan be improved, and productivity can also be improved.

1-22. (canceled)
 23. A method for manufacturing a wiring substrate,comprising steps of: loading a conductive sheet having a first facewhere conductive pillars are formed, an insulating resin sheet, and areleasing sheet to a gap of a pair of rolls having a substantiallyparallel rotating axis so that the insulating resin sheet is interposedbetween the first face of the conductive sheet and the releasing sheet;and adjusting the gap between the rolls so that the conductive pillarspierce the insulating resin sheet.
 24. An apparatus for manufacturing awiring substrate, comprising: a holding means having a planar surfacefor holding an insulating resin sheet having a first face and a secondface, the holding means to aspirate the first face of the insulatingresin sheet on the planar surface; a housing for storing a conductivefoil, the housing having an opening for introducing the holding meansholding the insulating resin sheet; a transporting means fortransporting the holding means into the housing through the opening, thetransporting means piling the insulating resin sheet onto the conductivefoil; and an adjusting means for adjusting a pressure inside the housingso that the pressure inside the housing is higher than a pressureoutside the housing.
 25. An apparatus for manufacturing a wiringsubstrate as set forth in claim 24, further comprises a cleaning meansfor cleaning the second face of the insulating resin sheet, and thecleaning means are formed outside of the opening of the housing.
 26. Anapparatus for manufacturing a wiring substrate as set forth in claim 25,wherein the cleaning means has at least an aspirating slit elongatedwith the opening.